The present invention relates to a network routing system and a routing apparatus for use with the network routing system, which can assure the quality of service in communicating a number of packets that satisfy the specified conditions.
In recent years, the rapid spread of personal computers or the Internet has been very striking, and an IP (Internet Protocol) network as the company network is also expanding now. Many carriers have started the IP services, and the network protocols tend to be unified into the IP.
For the applications, the electronic mail or WWW (World Wide Web) has come into wide use, or the multi-media data such as motion picture or sound has become popular. The IP has been mostly adopted as the protocol for use in the data communication.
Conventionally, there are two main ways of assuring the QoS (Quality of Service) in the IP network. One of them is employed for the distribution data of motion picture by the contents distribution server, for example, and is based on an RSVP (resource reservation protocol) as the QoS set-up protocol for assuring the QoS by reserving a network resource such as band for every specific flow (session) distinguished by the destination IP address, protocol ID, or destination port number. RSVP is a protocol as standardized by an organization of standardization IETF (Internet Engineering Task Force) for the Internet engineering. As one example, for the continuous stream data such as motion picture or sound, the RSVP is used to reserve a network resource such as transmission band on the transmission path from the transmitting server to the receiving client, and the delay or jitter is suppressed within a certain limit to enable reproduction of smooth sound or motion picture without depending on the conditions of traffic load on the transmission path, so that a required QoS can be realized. Lately, the network equipment with RSVP mounted or the multi-media applications coping with the RSVP have been put on the market, and an OS (Operating System) for the PC (Personal Computer) is configured to cope with the RSVP.
The other way of assuring the QoS is using a TOS (Type Of Service) field contained in an IPv4 header, in which the transfer processing in the network equipment is changed for each value of the TOS field to realize the quality of service differentiated for the packet transfer. The TOS field is provided within the IP header. There might be some provisions, for example, such as to transmit or transfer the packets of routing information prior to other information, but they have hardly spread, and the TOS field has been differently interpreted for each vendor. To redefine this, Diffserv (Differentiated Service) has appeared on the market. This redefines the previous usage of the TOS field contained in the IP header, in which the packet transfer is differentiated by changing the rate of abolition within the network equipment for each value set in the TOS field. For instance, ISP (Internet Service Provider) may provide in accordance with the contract with the user, a secure packet transfer service with high QoS to the user of high charge, or provides a packet transfer service of best effort to the contract user of regular charge.
Besides the IP packet transfer as the multi-media data or ISP service, some data communications are needed to assure the high QoS including a small delay. For instance, in the company network, the data communication of basic business activities including the order entry or accounting is highly important for the company, and is required to have high quality of transmission with small delay. Such communication is required to have architecture for transmitting the data with small delay and low loss at any time through a unit for assuring the band without regard to the network condition of traffic load between the client terminal and the host computer. Further, from the viewpoint of reduced network management costs, these basic business activities are shifting from the conventional SNA (System Network Architecture) or FNA (Fujitsu Network Architecture) to the IP identical to other information communication protocols for the electronic mail or WWW.
However, from the stand point of reduced network management costs, there is a strong demand for integrating the information communication such as WWW or the electronic mail and the basic service communication based on the IP, but in particular, the WAN (Wide Area Network) having slow transmission rate is subjected to other traffic loads of information communication, so that the excellent response of the basic service data communication is impeded. Therefore, in the current state, a private line is laid separately from the information communication to assure the quality of transmission in the basic service data communication in respect of small delay and so on.
By the way, using the RSVP as described above, the band can be reserved expressly, but is intended for a specific flow, or the special application data which the user terminal transmits to the specified destination address. The RSVP is mainly applied to the multi-media data that occur successively and have certain traffic characteristic. Accordingly, the RSVP is not suitable for the order entry or accounting activities which take place at a number of terminals sporadically located at various sites. Generally, the RSVP needs to have a process for discriminating the flow based on the IP address, protocol ID, or port number, which may impose great processing loads on the network equipment. Also, it is usually necessary to transmit or receive a signaling of the RSVP between the end systems for communication. In the cases where the RSVP was not supported by the end system, there was no method of reserving the resource such as the band of network in dynamical and explicit manner.
Also, using the Diffserv or TOS, the preferential transfer service can be implemented by the transfer processing method with the network equipment for a group of packets having the same value of DSCP (Differentiated Service Codepoint or of TOS field, but not limited in a specific flow. Unlike the RSVP, the Diffserv or TOS effects no signaling, and there is no architecture for reserving a network resource such as band on the network path and allocating the network resource to transfer the group of packets, so that the quantitative services cannot be provided. Accordingly, in the current state, there is no architecture for allocating explicitly the network resource such as band to a group of packets transmitted from a number of clients or applications located randomly to provide the services with the high QoS.
For example, it is common that the service communication in the company network is performed between a few mainframe host computers (Servers) and a total of several hundreds to several thousands of client terminals. Though there is the need of assuring the QoS for the service communication that is the most important for the company, differently from the WWW traffic, electronic mail, or FTP (File Transfer Protocol) traffic, it is practically impossible to install various programs required to implement the RSVP or Diffserv in a total of several thousands of client terminals, or replace the terminals, and it was almost difficult to assure the QoS.
Further, in the Internet, the user makes dial-up connection to the ISP from the residence to receive variety kinds of services, but if the high QoS service is provided to the user, the user terminal or application is necessary to cope with the RSVP or Diffserv. In order to provide or accept the fair service, there is the need of having architecture for providing the service of high QoS not only on the user side but also on the ISP side. In this way, the architecture for assuring the high QoS is required over the entire network including the individual user terminals, but no architecture has been prepared in the state of the art.